1. Field
Example embodiments relate to semiconductor memory devices, and more particularly, to nonvolatile memory devices and nonvolatile memory device operating methods.
2. Description of the Related Art
A semiconductor memory device is a memory device which is fabricated using semiconductors such as silicon (Si), germanium (Ge), gallium arsenide (GaAs), indium phosphide (InP), and the like. Semiconductor memory devices are classified into volatile memory devices and nonvolatile memory devices.
Volatile memory devices may lose stored contents at power-off. The volatile memory devices include static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), and the like. The nonvolatile memory devices may retain stored contents even at power-off. Nonvolatile memory devices include read only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable and programmable ROM (EEPROM), flash memory devices, phase-change RAM (PRAM), magnetic RAM (MRAM), resistive RAM (RRAM), ferroelectric RAM (FRAM), and the like. A flash memory device is roughly classified into NOR type and NAND type.
A semiconductor memory device with a three-dimensional array structure has been developed to improve the integration density of a semiconductor memory device.